Amnesia: The Dark Descent (2010)

The game, set in 1839, casts the player in the role of Daniel, a young man from London, who awakens in the dark halls of Prussian Brennenburg Castle with little to no memory about himself or his past. All he can remember is his name, that he lives in Mayfair and that something is hunting him. Shortly after waking, Daniel finds a note written by himself that explains how he purposely made himself forget his past, because he couldn't handle losing his innocence, so he wanted to forget it all. The note urges Daniel to descend into the castle's Inner Sanctum and murder a man named Alexander , the baron of the castle. The note gives a final warning that a "living nightmare" is chasing him, and Daniel must escape it for as long as he can because there is no way to fight back.